Scottish Crime and Justice Survey 2012/13: Drug Use

Annex 2: Self-Completion Methodology

This section provides more detail about the self-completion section of the questionnaire for the SCJS 2012/13 specifically for the questions covering illicit drug use. Details are also included about the self-completion interview, the weighting used on the data and the classifications of illicit drugs used in this report.

Further information about the design of the SCJS is contained in Annex 2 of 2012/13 Scottish Crime and Justice Survey: Main Findings report and in the accompanying Technical Report.

A.2.1 The self-completion interview

Fieldwork for the SCJS 2012/13 was continuous and took place between the 1st of April 2012 and the 31st of March 2013.

Interviews were conducted face-to-face in-home and were administered by specially trained professional interviewers working for TNS BMRB using Computer Assisted Personal Interviewing (CAPI). For the self-completion interview, the questionnaire was completed by respondents on the interviewer's tablet PC (Computer Assisted Self-completion Interviewing - CASI). This ensures confidentiality when answering sensitive questions or those on illicit behaviour. The respondent was asked to follow the instructions on the screen of the tablet PC and enter their answers using a special pen to tap the touch screen appropriately.

85% of respondents completed the self-completion section and of those 66% entered their answers directly into the tablet PC themselves and 19% asked the interviewer to administer the questionnaire for them.

The average questionnaire length of the self-completion section was nine minutes and 41 seconds.

A.2.2 Questionnaire Content

The SCJS 2012/13 consists of three elements:

• The main questionnaire consists of a set of core modules asked of the whole sample, including demographics; and a set of full and quarter-sample modules, containing questions on a variety of topics;
• A victim form questionnaire which collects details about the separate incidents a respondent may have experienced during the reference period. This victim form can be repeated up to five times. The number of victim forms completed depends on the number and nature of incidents respondents experienced;
• A self-completion questionnaire covering sensitive issues, including illicit drug use. All respondents were asked to complete a self-completion questionnaire, but had the option to refuse this due to the sensitive nature of the questions.

Respondents to the self-completion questionnaire on illicit drug use were first asked whether they had used any of the 17 illicit drugs/drug groups ever and also whether they had taken the fictitious drug semeron. Those respondents who have taken drugs in the past are then asked if they have taken them in the last 12 months and, for those who have, whether they have taken them in the last month.

A series of follow-up questions are asked for the different groups, including:

• For those ever using, which drug was the first ever taken; at what age they first took drugs, and what methods of drug taking they have ever tried;
• For those using in the last 12 months, whether they have mixed these drugs, consumed alcohol at the same time as taking them, how they would describe their usage, and whether they have taken anything else in the last 12 months which they thought was a drug;
• For those taking drugs in the last month, which one they have taken most often, how difficult it is to get hold of, where they obtained it the last time they took it, and, in the last month, how many times they have used it, whether they felt dependant on it, tried to cut down and whether they managed to.
• Those who have ever used cannabis, cocaine, ecstasy, tranquiliser or amphetamine, but not used any drugs in the last 12 months are asked at what age they last took it, whether they have ever felt dependant on any of the drugs they have ever taken, and which ones, as well as, for those who have felt dependant, whether they received any help in stopping taking them and from whom.

The questions about which drugs respondents have taken are asked in a loop (i.e. 'have you ever taken <drug name>?) rather than by selection from a single list of drugs.

A.2.3 Disclosure of sensitive information

Given the sensitive nature of the questions, especially as the majority of the questions on illicit drug use were on offending behaviours rather than victimisation (as opposed to the remainder of the self-completion questionnaire and the main questionnaire), a separate 'Don't wish to answer' button was provided at the top of the screen at every question in the self-completion section of the questionnaire.

At the start of the questions on illicit drug use, respondents were reminded that the answers they gave were completely confidential, reminded not to answer the questions including any drugs for which they had a prescription, and asked to answer the questions honestly:

"The following questions ask whether or not you have ever used drugs. Please answer them honestly. The answers you give are completely confidential. Please DO NOT tell us about drugs you have been given on prescription."

A.2.4 Drugs Classification

The classifications of drugs used in this report are detailed in section 1.5. However, there are two points of clarification which readers should note:

1. Amphetamines can be classified as either Class A (when prepared for injection) or Class B (in powdered form). Since questions used in the SCJS do not distinguish between the forms of the drug taken for the purposes of analysis, the report assumes that all amphetamine use is of the Class B type. This is consistent with the approach adopted by previous surveys, including the 2008/09 and 2009/10 SCJS.

2. The category "not classified" indicates that possession of these substances (poppers and glues, solvents, gas or aerosols) is not illegal but it is an offence to supply these substances if it is likely that the product is intended for abuse.

A.2.5 Non-response to the self-completion section

10,235 (85%) respondents to the main survey answered the self-completion questionnaire. Table A2.1 compares the profile of respondents who answered the self-completion section of the questionnaire (including those who did so where the interviewer administered the questionnaire) and those who did not answer it:

• The table shows that there was no difference between men and women in conversion from the main interview to self-completion. However, the proportion of those completing the self-completion section decreased as the age group of the respondent increased, falling from 93.2% for 16 to 19 year olds to 62.8% for those aged 85 or older.

The most common reason for non-completion of the self-completion questionnaire given by respondents was running out of time (mentioned by 54%). Only 3.5% of respondents refused to complete the self-completion questionnaire because of worries about confidentiality.

Comparing the profile of respondents who completed the self-completion section in the SCJS 2012/13 (85%) to the previous two sweeps of the SCJS in 2010/11 (85%) and in 2009/10 (84%) shows that the response rate has remained very level. However, the response rate to the SCJS 2008/09 self-completion questionnaire was markedly lower at 69%. There is an ongoing trend evident in the SCJS 2012/13 and from the previous three sweeps of the SCJS where equal percentages of males and females completed the self-completion section and the percentage of respondents who answered the self-completion questionnaire decreased as age increased.

All data from the self-completion section has been weighted in order that the sample is representative of the population (see A.2.7).

Table A.2.1: Proportion of respondents completing self-completion section by age and gender

SCJS 2012/13

% of respondents participating in self-completion section	Male	Female	Overall
16 to 19	93.5	92.9	93.2
20 to 24	85.3	87.6	86.6
25 to 29	87.6	85.9	86.6
30 to 34	87.5	87.3	87.4
35 to 39	87.5	87.3	87.4
40 to 44	84.2	86.1	85.3
45 to 49	83.9	89.5	87.1
50 to 54	86.4	89.7	88.2
55 to 59	90.1	86.5	88.1
60 to 64	81.6	87.4	84.8
65 to 69	86.6	87.8	87.2
70 to 74	83.7	82.4	83.0
75 to 79	81.1	74.9	77.5
80 to 84	78.0	69.8	72.8
85 plus	65.5	61.4	62.8
Overall	85.0	85.0	85.0

A.2.6 Sample Profile

Table A2.2 provides the profile of the achieved sample of the self-completion section of the SCJS 2012/13 before weighting was applied and the weighted sample profile. In the SCJS 2012/13, men were underrepresented in the sample particularly men aged 16-24 and 25-44. Women aged 16-24 were under-represented in the sample but women in the remaining three age groups were over-represented. Weighting was applied to ensure that the sample was representative of the population.

Table A2.2: Unweighted and weighted sample profiles by age and gender

SCJS 2012/13

Percentage	Unweighted Sample[38]	Weighted sample[39]
Men
16-24	3.8	7.3
25-44	12.8	15.8
45-59	11.5	12.3
60+	15.2	12.5
Base	4,420	2,078,490
Women
16-24	4.6	7.1
25-44	17.6	16.2
45-59	15.2	13.2
60+	19.3	15.7
Base	5,800	2,258,730
All men	43.2	47.9
All women	56.8	52.1
Base (all respondents)	10,240	4,337,220

Base: All respondents to self-completion questionnaire (10,240)

A.2.7 Weighting

The data from the SCJS 2012/13 was weighted by the Scottish Government in order to correct for unequal probabilities of selection and variations in response rates from different groups. Calibration weighting was used to derive weighted survey totals which match known population totals.^[40] Separate weights were required for the self-completion section since not all respondents to the main section of the survey SCJS completed the self-completion section. The individual weight was applied to all of the questions included in this report as they all related to the experiences and opinions of individuals.

All data in this report is weighted data with the original base size provided in figure headings.